This invention relates to PAF antagonists (platelet activating factor antagonists). More specifically stating, the present invention relates to a PAF antagonist containing a compound of the formula (I): ##STR2## [wherein A stands for an optionally substituted phenyl group or an optionally substituted heterocyclic group; X stands for a methylene group (--CH.sub.2 --), carbonyl group (--CO--) or thiocarbonyl group (--CS--); R.sup.1, R.sup.2 and R.sup.3 each stand for a lower alkyl group] or a salt thereof.
This invention also relates to a novel 1,4-disubstituted piperazine compound of the formula (I) [wherein A stands for an optionally substituted 2,3-dihydro-1-benzosepin-4-yl group; X, R.sup.1, R.sup.2 and R.sup.3 are of the same meaning as defined above] or a salt thereof, which is useful as a PAF antagonist, and production thereof.
PAF has a phospholipid structure and is a chemical transmitter existing in a living body. It has been made clear that PAF is, in a living body, closely concerned with allergy, anaphylaxis, inflammation, etc., and it has also been known that PAF has a strong hypotensive activity and platelet agglutinating activity. On administering PAF to an animal, the animal may in some cases be killed from shock. Symptoms caused by the shock from PAF have much resemblance to those caused by the shock from endotoxin, and it has been considered that PAF is concerned with the endotoxin shock.
On the other hand, while a variety of compounds having PAF-antagonistic activity have been known, very few of them are satisfactory in PAF-antagonistic activity in a living body. And, even when the PAF antagonistic activity in a living body is satisfactory, not a few of those compounds have some restrictions in the administration method.